Facebook is not against Bitcoin but rather intends to avoid the situation of misleading its community members through its paid advertisement. Users of facebook can post crypto and Bitcoin related topics on facebook without any penalty.
Obviously the Facebook is against bitcoin and again the reason is its volatile nature, this is human psychology that when the valuation of bitcoin is low people started calling it a scam or a bubble that would burst soon and due to its criticism, Facebook has banned crypto ads from its page so that it may not loose its users and following Facebook , Twitter has also banned it but the result are now according to them as after banning crypto ads, the shares of Facebook has deflated and this much potential bitcoin possesses.